I suggest you ...

Be able to add a "New Client" when checking the time they would like, rather than having to ask everyone if they have been before.

When someone calls, you always check the time they wold like if free. But if they are new, you have to create an account for them first, which means then leaving the schedule screen to enter a few details for the owner and dog, and going back to find the appointment time again.

If we could add a sort of "temporary" booking details, and compete a new account when the owner comes in, this could save a lot of swapping screens and questions for the client.

It would also avoid the risk of offending people if you don't remember them, and they have actually been a lot before.